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eBay users targeted by advanced Trojan

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Updated eBay users are being targeted by an advanced Trojan that attempts to redirect traffic so it can silently bid on a car from the auction site's car section, Symantec is warning. It is the latest security headache for eBay, which has faced an onslaught of complaints from some users who say fraud on the site has increased to unacceptable levels over the past few months.

eBay officials are aware of the Trojan and are working with Symantec to prevent it from affecting buyers and sellers, a spokeswoman said.

Trojan.Bayrob implements a proxy server so that traffic intended for eBay is instead sent to one of several sites controlled by the attacker. Traffic is redirected by changing settings corresponding to at least six eBay URLs in the victim's hosts file. Once connected to rogue servers, Bayrob is programmed to download configuration data, including a variety of php scripts.

At least one of the scripts, Var.php, downloads variables such as tokenized versions of eBay pages designed to dupe a victim into thinking they are legitimate. One such page spoofs eBay's "Ask a question" section, which allows prospective buyers to - wait for it - ask sellers questions.

The tokenized variables let the attacker dynamically replace key strings such as the seller's name with ones doctored by the attacker, lending power and authenticity to the scheme. There are also feedback pages, for example, with high ratings, which are designed to give the victims confidence in the attacker and complete an auction.

This man-in-the-middle approach is unusual for eBay attacks, which usually involve phishing traps or keyloggers. But getting code to execute properly in man-in-the-middle attacks is difficult, and Symantec said the rogue servers did not appear to be returning variables needed to actually generate the spoofed pages.

eBay security has suffered several black eyes dating back to at least December, when longtime users say the number of fraudulent auctions being offered by users with high ratings began to grow. A hacker who goes by the name Vladuz has also embarrassed eBay security officials by gaining unauthorized access to servers on at least two occasions. The breaches allowed him to mock the company even as he posed as one of its employees.

eBay representatives have said Vladuz was able to penetrate only a limited section of eBay's system that is not able to access customer records and other sensitive information. They have also said most hijacked accounts are the result of users falling for phishing emails. ®